<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>css测试</title>
    <!--    引用css文件-->
    <link rel="stylesheet" type="text/css" href="4.css"/>
</head>
<body>
<div id="id0001" class="class01"> 你好世界</div>
<div id="id0002" class="class02"> 你好世界</div>
<span id="id0003" class="class01">你好</span>
<span id="id0004" class="class02">世界</span>
</body>
</html>